Teenage climate change activist Greta Thunberg had one question for the global leaders assembled at the United Nations: “How dare you?”

Days after telling U.S. lawmakers “listen to the scientists,” she made the same demand on an international scale. Thunberg chastised leaders for praising young activists like herself while failing to deliver on drastic actions needed to avert the worst impacts of climate change, and warning that if the world continued with business as usual, her generation would face an insurmountable catastrophe.

“This is all wrong,” she told a U.N. climate meeting in New York on Monday. “I shouldn’t be up here. I should be back in school on the other side of the ocean. Yet you all come to us young people for hope. How dare you.”

Thunberg, a 16-year-old activist who began skipping school in her native Sweden a year ago to protest climate change, has quickly become the face of a global movement of young people demanding their elders ensure their planet’s future. On Friday, millions of young people all over the world joined Thunberg in a climate strike, which she led from New York City.

Thunberg continued her relentless campaign on Monday, telling the U.N. that “you have stolen my dreams and my childhood with your empty words.”

“People are suffering, people are dying, entire ecosystem are collapsing,” she said. “We are in the beginning of a mass extinction and all you can talk about is money and fairy tales of eternal economic growth. How dare you.”

“For more than 30 years, the science has been crystal clear,” Thunberg said. “How dare you continue to look away and come here and say you’re doing enough when the politics and solutions needed are still no where in sight. You say you hear us and that you understand the urgency but no matter how sad and angry I am, I do not want to believe that, because if you really understood the situation and still kept on failing to act, then you would be evil and that I refuse to believe.”

Her remarks ended with a warning: “You’re failing us, but the young people are starting to understand your betrayal. The eyes of all future generations are upon you. And if you choose to fail us, I say, we will never forgive you.”